Geologia do Corpo Intermediário/Máfico Umari, NW do Domínio Rio Piranhas-Seridó

Abstract

The Ediacaran magmatism (~ 600 Ma) that occurred in the Rio Piranhas-Seridó Domain was aperiod of intense granitic plutonism, expressed in the form of plugs and batholiths, and was related to the formation of the paleocontinent Gondwana. Within this context the Quixaba Granitoid is a NE-SW strike batolith, dominated by monzonite rocks and a semicircular ocurrence of diorite rocks at its center, the Intermediate/Mafic Umari Body, theme of this work. Previous authors define two facies for the Quixaba Granitoid. Themonzonitic nature rocks corresponds to the Quixaba Facies and the dioritic rocks corresponds to the Umari Facies. The present work seeks to characterize thegeometry and processes of emplacement of the Intermediate / Mafic Umari Bodyand recognize the rocks components of it. An analysis of cartographic products (remote sensing and geophysical images) was carried out and integrated with field mapping observations. The Intermediate / MaficBodyisa body with a higher E-W ratioandabout 4km2of outcrop area. It is composed of dioritic rocks with orthopyxenee clinopyrxeneand hybrid rocks,products of different degrees of mixing between the Quixaba and Umari Facies. Typical hybridization features such as MME's, rapakivi, ocellar quartz, mixed apatite morphologies, synneusis, multiple zonation and mafic clots in the hybrid rocks confirm this interpretation.